Recently, a dye sensitization solar cell has been considered as promising as a future inexpensive solar cell. As illustrated in FIG. 20, a dye sensitization solar cell includes, as a basic structure, a porous semiconductor layer 204 impregnated with a sensitizing dye and an electrolyte layer 206 between a transparent electrode (negative electrode) 200 and a counter electrode (positive electrode) 202.
Here, the semiconductor layer 204 is divided into a plurality of cells together with the transparent electrode 200, the electrolyte layer 206, and the counter electrode 202, and formed on a transparent substrate 208 in which the transparent electrode 200 is interposed between the semiconductor layer 204 and the transparent substrate 208. The rear surface side of the counter electrode 202 is covered by a counter substrate 210. The transparent electrode 200 of each cell is electrically connected with a neighboring counter electrode 202 and the plurality of cells are electrically connected with each other either in series or in parallel in an entire module.
In the dye sensitization solar cell configured as described above, when visible light is illuminated from the rear side of the transparent substrate 208, the dye impregnated in the semiconductor layer 204 is excited to emit electrons. The emitted electrons are guided to the transparent electrode 200 through the semiconductor layer 204 and then emitted to the outside. The emitted electrons return to the counter electrode 202 via an external circuit (not illustrated) and are received in the dye in the semiconductor layer 204 again via the ions in the electrolyte layer 206. In this manner, optical energy is immediately converted into electric power which is in turn output.
In a process of fabricating such a dye sensitization solar cell, a method of immersing the porous semiconductor layer 204 formed on the transparent substrate 208 in a dye solution so as to adsorb sensitizing dye into the porous semiconductor layer 204 has been employed in the related art.